We are using the direct methods protocol in SHELX-86 to find heavy
atom sites, and have had some success with it. Have a look at the SHELX-86
manual if you have it - Sheldrick discusses this application a bit. He and
Ward Robinson have also written a short article in the IUCr series on
Crystallographic Computing (Vol.4, pg366-377, 1988) where they have a very
short discussion on page 373-374. I can provide you with info. on how we do
it if your interested.
University of Saskatchewan